Multi-Object Projection Mapping Example

These are actual 3D shapes made from white card and glue, placed on a table in front of a projector.

To do this, I make the same model in a virtual world on the computer with a virtual camera. The virtual camera in placed in the 3d world in the same place as the projector with the same rotation. The virtual camera is carefully adjusted so it has the same properties as the real projector such as throw ratio, zoom, field of view and X/Y shift. I then 'look' through this virtual camera and send what it sees to the projector. Inside the virtual world I texture map video onto the 3d scene and do some generative visuals based on their shape. Now when we look at the model in the real world it is covered perfectly in the projection from the computer.

Complicated stuff but once you have worked out you virtual camera settings and content management it is very easy to apply this to any 3d scene, even real world objects such as buildings or flowers.